Is advisory notice applicable to a subcontract manufacturer ?

Answer:

Even though your company might not be the product owner, Advisory Notice is still applicable for your organization as a manufacturer of the device.
For example, in the situation where there is some field safety corrective action, you might be required to take part in the investigation and hence it is recommended for you to have a procedure for this in order to be compliant with ISO 13485 and local regulatory requirements in your country.

For more information, you might refer to:

How to manage recalls and advisory notices for medical devices according to ISO 13485

https://advisera.com/13485academy/blog/2017/08/31/how-to-manage-recalls-and-advisory-notices-for-medical-devices-according-to-iso-13485/